Electromagnetic relay



June 1954 H. M. KNAPP ETAL 2,682,585

ELECTROMAGNETIC RELAY Filed May 24,1952

H M. KNAPP c. E SPAHN, JR.

By 0mm ATTORNE V Patented June 29, 1954 UNITED STATES PATENT OFFICEELECTROMAGNETIC RELAY Application May 24, 1952, Serial No. 289,843

Claims.

This invention relates to switching devices, and more particularly toelectromagnetic relays.

An object of this invention is to improve the efficiency, thecompactness and the economy of manufacture and maintenance ofelectromagnetic relays.

A further object of this invention is to increase the capability of arelay to meet a plurality of diverse circuit requirements.

A feature of this invention is a unitary means for accuratelypositioning the legs of a relay core, for defining the position of restof a relay armature and for adjustably supporting certain of the contactmaking elements of a relay.

Another feature of this invention is a structural arrangement wherebythe types of contact combinations in a relay are determined by theconfiguration of a single readily replaceable element.

Another feature of this invention is a means for assisting the restoralof a relay armature to its normal position without impeding thecontactcontrolling operation of the armature.

The manner in which the above-noted objects are attained and the natureof the listed features may be comprehended from the following detaileddescription of a preferred embodiment of the invention when read withreference to the accompanying drawings in which:

Fig. 1 is a plan view of a preferred embodiment of the inventionpartially cut away to show certain details of the construction moreclearly;

Fig. 2 is an elevational view of the relay shown in Fig. 1; and

Figure 3 is a front-end view of the relay shown in Fig. 1. d

The relay herein disclosed is also disclosed and described, and certainfeatures thereof claimed, in the patent application of H. M. Knapp,filed on even date herewith, S. N. 289,842.

The relay disclosed in the accompanying drawings comprises an E-shapedcore having three leg portions l, 2 and 3 and a bridging portion 4 whichserves to interconnect the leg portions I, 2 and 3. Removably placedupon the center one of these leg portions 2 is an electromagnetic coil 5having a front spoolhead 6. The terminals of the coil 5 are connected towires 1 which are mounted in the front spoolhead 6 and extend rearwardlyof the relay through apertures in a molded element of insulatingmaterial 8 and appear at the rear of the relay as terminals to whichexternal circuits may be connected. A plurality of these terminal wires1 are provided so that coils having multiple windings may be employed ifde sired.

The molded block 8 is substantially L-shaped in cross-section (the Lbeing inverted in the showing of Fig. 2) whereby a flat surface isprovided against which the upper side of the bridging member 4 of thecore may rest. However, interposing the upper surface of the bridgingmember 4 and this surface of the molded block 8 is a fiat- U-shapedspring member 9. By virtue of this construction, the bight of theU-shaped spring member 9 is clamped between the lower surface of theoffset portion of the molded block 8 and the upper surface of thebridging element 4 of the core. 1

The two leg portions of the spring member 9 extend forwardly in spacedproximity to the outer core legs I and 3. The extreme forward ends ofthe legs of the spring member 9 are provided with extending flangeportions which may be wrapped or clinched around the tip ends of thelegs ID of the armature II whereby the spring member 9 serves as a meansfor hinging the armature and for biasing that armature to its unoperatedposition. The clinched ends of the legs of the spring member 9 mayfurther be attached to the legs ll] of the armature II by welding, ifdesired.

The armature I I is essentially U shaped in appearance, the bight of theU extending across the relay so as to be capable of bridging the threelegs I, 2 and 3 of the core. The leg portions ID of the armature IIextend rearwardly of the relay and the tip ends of the legs I0 restagainst the legs of the spring member 9, which in turn rest against theouter core legs I and 3. Therefore, the armature II is pivotallymounted, the fulcrum being approximately at the extreme ends of the legsIn of the armature l I. The legs I0 of the armature II may be of anysuitable length depending upon the operational requirements of therelay.Thus, in the embodiment of the invention disclosed in Figs. 1, 2 and 3,the armature legs have been made substantially as short as possible andstill provide a sufficient air-gap between the bight of the relay II andthe central core leg 2.

It will be seen that the electromagnetic circuits of the relay include afirst circuit comprising the center core leg 2, the core bridging member4, the outer core leg I, leg I0 and the bight of the armature I I, andan air-gap between the armature and the core. A similar path existsincluding core leg 3 and the other leg IU of the armature l I.Therefore, upon energization of the coil 5, a force will be exertedtending to pivot the armature II to 3 a position in which it bridges thethree core legs l, 2 and 3, i. e., the forwardmost edge of the armatureH will tend to move downwardly to engage the core, in the showing ofFig.

Three layers of contact-holding elements are provided, and in thepreferred embodiment of the invention these contact-holding members arein the form of thin wires. The lowermost layer 50 and the uppermostlayer 52 of wires are movable, under the control of the armature,relative to the centermost layer of wires i. As may best be seen in Fig.2 of the drawings, the lowermost set of these wires 50 is molded orotherwise mounted in an insulating member l2 which engages the upperedge of the molded block 8. The centermost layer of wires 5!, which arepreferably of heavier construction than the lower and upper layers ofwires, are mounted in an intermediate block of insulating material Itwhich rests on block [2. To provide the requisite rigidity, it isadvantageous to provide a forward extension Id for the block H. Thecenterinost layer of wires 5| are preferably mounted in the block I3 andin its forward extension I l during the operation in which blocks l3 andM are molded. Similarly, the upper layer of springs 52. are molded orotherwise afiixed in an upper molded block of insulating material l5which abuts the upper surface of block It. Abutting the upper edge ofmolded block i5 is an essentially U-shaped balancing spring member Hi,the function of which will hereinafter be described.

In order accurately to position and retain the bridging portion 4 of thecore, the molded blocks 8, l2, l3 and i5 and the balancing spring It infixed position relative to one another, it is ad vantageous to providecorresponding projections and indentations in the several elements. Forexample, the balancing spring member 16 is apertured to engageprojections ll on the upper bloclr. l5. This group of elements is firmlyrendered integral by means of a clamp which has a top portion I8 and twoleg portions IS). The top portion l8 firmly engages the upper surface ofthe balancing spring member I6 and the leg portions l9 are provided withinwardly extending projections which engage the edges of theunder-surface of the bridging portion 4 of the core. The upper surfaceit of the clamp may be suitably deformed to provide a spring action.

The centermost layer of spring members 5i are afiixed, preferably duringthe molding operation, in a front molded block member 23, and passthrough that front molded block 23. Springs 5| are provided at theirforwardrnost ends with contact elements 26. As may best be seen in Fig.3 of the drawings these contact members 24 are preferably square orrectangular blocks of metal with relatively thin layers of precious orsemi-precious contact metal at their upper and/ or lower edges.

In order that the centermost layer of fixed springs 5i, which areintegral with the front molded block 23, may be securely immobilized, acore plate 25 is provided. This core plate performs a plurality offunctions. It is affixed to the front ends of core legs i, 2 and 3 byapertures in the plate 25 securely engaging these legs. This serves notonly to retain the core plate in position, but also greatly improves theecononly of manufacture of the relay. The three apertures in the coreplate 25 which engage the core legs I, 2 and 3, may be accuratelylocated at relatively small cost. When the core plate is assembled tothe core, the core plate then serves accurately to position the threelegs I, 2 and 3 of the core with relation one to the other. Therefore,there is no necessity for machining the core legs to close tolerancesand no necessity for maintaining the upper surfaces of the core legs I,2 and 3 accurately in a plane. The core plate serves to force thoseupper surfaces to be ccplanar when the relay is assembled.

A portion 26 of the core plate 25 is bent forwardly so as to rest inproximity to a central forward extension 2'! of the armature ll. Thisprojection 26 serves as a back stop for the armature, i. e., it definesthe unoperated position of the armature. By virtue of this constructionthe back stop is centrally located on the armature and is positioned inline with the member 30 upon which the armatures force is exerted. Ithas been found that if the line of the armatures output force passesthrough the back stop mem ber, armature rebound is substantiallyobviated.

The core plate 25 is also provided with two projecting arms comprisinghorizontal portions and 46 and vertically extending portions 41 and 48.The front molded block 23 rests against the uppermost edges of theupstanding arm portions 41 and 48, being firmly held against thoseportions primarily by the downward force exerted by the pretensionedsingle fixed springs 5! and also by the downward force exerted by thepretensioned twin springs 52. The horizontal portions 45 and 48 areapertured so that a tool may be inserted to bend the horizontal portions45 or it up or down to adjust the position of the front molded block 23and thus to adjust the position of the fixed contact elements 24relative to the movable springs 50 and 52.

The upper and lower spring members 52 and 50, respectively, extendforwardly in approximate parallelism with one another and with the fixedsprings 5|, are provided with downwardly and upwardly extending offsetportions, respectively, at theirforwardmost ends, and terminate inprecious or semi-precious metal contact elements. As may best be seen inFig. 3 of the drawings, two upper springs 52 and two lower springs 50are provided for each contact element 24 of each fixed spring 51 so thatupon any contact closure two independent contacts engage a single fixedcontact. This construction reduces the possibility of malfunctioning ofthe relay clue to dust orother impediments.

The upper springs 52 and the lower springs 50 are controlled by a movingcard 30 of insulating material. The member 30 is generally rectangularin external configuration and is suitably apertured to perform itsnecessary functions. The upper layer of springs 52 rest against theuppermost edge 35 of the card 30; the lowermost layer of springs 50 areengageable by an edge 36 of the moving card 30. The card 30 is moveddownwardly upon the operation of the relay by virtue of an engagement ofa portion 31 of the card 30 with forwardly extending projections 38 ofthe armature H.

The uppermost layer of springs 52 are bent so as to be pretensioned in adownward direction. The upper springs 52 therefore continuously exert aforce downwardly on the moving card 30 so that upon the downwardmovement of card 30 as a result of the operation of armature II, theupper layer of springs 52 are permitted to move downwardly to engage thefixed contact elements 24. Similarly, the lower layer of springs 50 arebent so as to be pretensioned upwardly into engagement w th the fixedcontact elements 24.

Therefore, upon a downward movement of the moving card 30, the lowersprings 50 are forcibly separated from the fixed contact elements 24.Upon the release of the relay and the return of the armature I l and themoving card 30 to their normal positions, as shown, the upper layer ofsprings 52 will be forced back to their normal positions, as shown, andthe lower layer of springs 50 will be permitted to return to engagementwith the fixed contact elements 24.

The movement of the springs 52 and 50 both upon the operation and therelease of the relay is controlled not only by the moving card 30 butalso by the front molded block 23. Thus, a plurality of tooth-likeprojections 43 are provided on the upper surface of the front moldedblock and the upper movable springs 52 are accurately lat erallypositioned and guided thereby during their movement. Similarly, aplurality of projections 44 are provided on the lower surface of themolded block 23 to guide the lower springs 50 during their movement. Byvirtue of this arrangement, accurate lateral engagement of the movingsprings with the fixed contact elements is assured.

In certain uses of the relay the moving springs may be subjected tohigh-frequency vibratory chatter upon the operation or release of therelay. To avoid this condition, a shock absorbing material 54 may beafiixed to the portion 14 of the molded block l3 so as to press againstthe moving springs 50 and 52 to damp vibrations of those springs.

It will be noted that in the embodiment of the invention shown in Figs.1 to 3, which represent a relay of conventional size, there are twelvegroups or contact elements, each of which groups may comprise a fixedcontact element, an upper twin contact element and a lower twin contactelement. By virtue of the previously described operation, it will beperceived that the upper twin contact elements, mounted on the twinwires 52, are normally separated from the fixed contact elements 24 butthat upon operation of the relay these upper contact elements will bebrought into contact with the fixed contact elements 24, i. e., thefixed contact elements 24 and the upper contacting elements formso-called make combinations. If the edge 35 of the moving card 30 bestraight and parallel with the fixed elements 24, all of the uppermoving springs 52 will simultaneously engage all of the fixed elements24. However, in some uses of the relay it may be found to be desirablefor selected ones of the uppermost springs 52 to engage the fixedcontact elements 24 at earlier or later times than others of those uppersprings 52 engage others of those fixed contact elements 24. If a slightdepression such as 4| (Fig. 3) is made in the upper edge 35 of card 30,the springs 52A which engage that slight depression will obviously makecontact with their associated fixed elements 24 at an earlier point inthe course of the downward movement of armature I l than will others ofthe moving springs 52. These contacts may be labeled early makecontacts. Further, if an even deeper depression 42 be made in the edge35 of the moving card 30, the springs 52B engaging that deeperdepression will make contact not only prior to. the time at which thenormal springs 52 make contact with their associated fixed elements 24,but also prior to the time at which the early make contacts 52A engagetheir fixed elements 24. This latter group of springs 52B may be labeledpreliminary make contacts.

It will also be perceived that by virtue of the above-describedoperation of the relay, the lower movable spring elements 50 arenormally in contact with their associated fixed contacts 24 and thatupon the operation of the relay and the consequent downward movement ofarmature l l and moving card 30, this lower layer of springs 50 willbreak contact with their associated fixed elements 24. By providingsimilar discontinuities (not shown) in the surface 36 of the moving card30, early break contacts and preliminary brea contacts may also beprovided. Con-- versely in both the case of make and break contacts, ifthe surface 35 or 36 of the card 35 be provided with areas which projectupwardly or downwardly from the surfaces 35 or 36, respectively, latemake contacts and late break contacts may also be provided. However,three stages of make-contact and three stages of breakcontact operationare sufficient for substantially all circuit requirements.

Assuming that each upper set of twin springs 52 may be of the normal,early or prelimi nary type, and that each lower set of twin contactsprings 50 may also be either normal, early or preliminary, it ispossible to provide for any one of fifteen different possible contactarrangements for each set of contacts. Thus, by omitting the set oflower springs 50 there may be provided a normal make contact set, anearly make contact set or a preliminary make contact set. Similarly, byomitting the upper pair of twin springs 52, a normal, an early, or apreliminary break contact set may be provided. By using both the upperset of twin springs 52 and the lower set of twin springs 55 inconjunction with the fixed contact element 24, and by selecting whethereach of the upper sets and lower sets be normal, early, or preliminary,the following combinations of contact operation may, in an obviousmanner, be obtained: A break-make combination in which both the upperand lower sets are either normal, early or preliminary; an earlymake-break, or a preliminary make-early break or a preliminarymake-break combination, all normally called continuities, in which theupper set of twin wire contacts engages the fixed contact element 24either somewhat before or substantially before the time that the lowerset of contacts separates from the fixed contact elements 24; and anearly break-make, or a preliminary break-early make or a pre liminarybreak-make combination, all normally called transfers, in which thelower set of twin wire contacts 50 separates from the fixed contact 24either somewhat before or substantially before the upper set of twinWire contacts 52 en gages the fixed contact element 24. Similarly, theremay be early make-early break or preliminary make-preliminary breakcombinations.

These diverse combinations may be obtained primarily by the coding ofthe moving card 30, i. e., by the configuration of the surfaces 35 and36 of that card. If only make contact coinbinations or only breakcontact combinations are required, obviously either the surfaces 35 and35 of the card 35 must be so conformed that the springs never makecontact or never break contact, or else, more economically, one or moresets of springs 52 or 50 may be omitted or the contact elements may beremoved therefrom.

It will be seen that the possible combinations may be extendedco'ncatenatiously by the strapping the terminals of adjacent groups ofcontacts in the well-known fashion, whereby a plurality of complexcombinations such as make-befre-break-before-make may be obrained ifcircuit conditions require.

Referring again to Figs. 1 and 2 of the drawings, it will be noted thatthe armature l l is subjected to a plurality of forces. The spring .3exerts a force tending to maintain the armature in unoperated position,as shown in the drawings. The electromagnetic flux tends to move thearmature downwardly to bridge the core legs i, 2 and 3. The moving card30 exerts a down ward force on the armature due to the fact that themoving springs52 are pretensioned downwardly and consequently exert aforce on moving card 3!] in a downward direction. Balancing sp "ing 16,which is connected tomoving card 38, serves to exert an upward force oncard Sit therefore, an upward force on armature I l. The upward forceexerted by spring I6 is selected stantially to counterbalance the forceexerted by the moving springs 52 and consequently the force exerted bybalancing spring 16 must be varied in accordance with the degree ofpretensioning of the springs 52 and the number of springs til which areprovided.

In special uses of the relay, it may be desirable to have an additionalforce exerted on the ar ture tending to restore that armature to normal.If such force be required however, it normally disadvantageous to havethat force continually exerted inasmuch as such force would also opposethe movement of the armature during its operation. Buffer spring 55 isoperative to exert a force to assist restoration of the armature tonormal but does not impede the downward movement of the armature untilafter all contact operations have been completed. Buffer springessentially U-shaped, having a crosspiece '15 and two legs 51. Aprojection 58 (Fig. 2) extends upwardly from the crosspiece 56 andengages the lower edge of the middle core leg 2. The extreme ends of thelegs 51 of spring 55 press against the lower surfaces of the outer corelegs I and 3, and at a point on the buffer spring 55 intermediate theprojection 58 and the extreme ends of the spring legs 51, the springlegs 51 engage projections on the spoolhead 6. The projections on thespoolhead 6 are so located that the legs ill of the buiTer spring 55 areslightly deformed when the buffer spring is in position on the relay,and the resulting tension of the spring legs 5'! serves to retain thebuffer spring 55 in position. An additional upstanding portion 59 isprovided on crosspiece 56. This portion 59 is so located that the loweredge of the moving card will con tact it when the relay is operated.Consequently, 5?" st prior to the completion of the operation ofarmature l l, the moving card 30 will engage the buffer spring 55 andbend it downwardly. When the coil 5 is deenergized the buifer spring 55will be effective to exert an additional upward force to assist thereturn of the armature I I to normal.

While the use of twin contact elements mating with single contactelements substantially obviates the possibility of malfunctionin of therelay in the presence of dust or other impurities, contact cover 60 maybe provided further to insure proper operation and also to prevent darn.age through mishandling. This cover is arranged to engage the frontmolded block 23 on all four sides to create a substantially dust-tightenclosure for the contacts. It will be noted that since the contactcover 60 engages the upper extremes of the projections 43 and the lowerextremes of the projections 44 on the front molded block 23,

the contact cover also serves to insure that the springs 52 and will betrapped in their proper positions and yet that, upon removal of thecontacts, the springs 52 and 50 may be readily displaced so that themoving card 30 may be removed and a card of difierent surfaceconfiguration inserted for coding purposes.

It is to be understood that the above-described arrangements are butillustrative of the princi ples of the invention. Numerous otherarrangements may be devised by those skilled in the art withoutdeparting from the spirit and scope of the invention.

What is claimed is:

1. An electromagnetic relay comprising a core, an energizing coil onsaid core, a plurality of insulating members, means for clamping saidmern hers stacked relationship on said core, an armature, means forhinging said armature to core, a molded block, means connected to blocl:and. said core for fixing the position of 1 block. relative to saidcore, a plur, ty of ed contact springs molded in one of said. insulatingmembers and in said block, a first plurality of movable contact springsmolded an other one of said insulating members and extending in spacedproximity to and on one of said contact springs, a. second plurality ofmovable contact springs molded in another one of said insulating membersand extended. in spaced proximity to and on the other side of r l 1. xedcontact springs, and a movable opera ng engaging said armature andhaving t ice engageable with said first plurality of m vable Contactsprings and second surface en- 'eable with said second plurality ofmovable contact springs.

2. An electromagnetic relay comprising an E- shaped core having threecoplanar legs a bridging member, an energizing coil mounted on thecenter one of said legs, a spoolhead for said coil, a plurality ofinsulating members, means for clamping said insulating members and thebridg ing member of said core in stacked relationship, an armature,means for hinging said armature to said core, a molded block, a coreplate engaging said core and fixing the location of the ends of the legsof said core, a pair of extensions on said core plate engaging saidmolded block for fixing said block with respect to said core, aplurality of fixed contact springs molded in one oi said insulatingmembers and in said block, a first plurality of movable contact springsmolded in another one of said insulating members and extending in spacedproximity to and on one side of said fixed contact springs, a secondplurality of movable contact springs molded in another one of saidinsulating'members and extending in spaced proximity to and on the otherside of said. fixed contact springs, and a movable operating cardengaging said armature and having a first surface engageable with saidfirst plurality of movable contact springs and a second surfaceengageable with said second plurality of movable contact springs.

3. An electromagnetic relay comprising a core, an energizing coil onsaid core, aplurality of insulating members, means for clamping saidmembers in stacked relationship on said core, an armature, means forhinging said armature to said core, a molded block, means connected tosaid block and said core for fixing the position of said block relativeto said core, a plurality of fixed contact springs molded in one of saidinsulating members and in said block, a first plurality of movablecontact springs molded in another one of said insulating members andextending in spaced proximity to and on one side of said fixed contactsprings, a second plurality of movable contact springs molded in anotherone of said insulating members and extended in spaced proximity to andon the other side of said fixed contact springs, a movable operatingcard engaging said armature and having a first surface engageable withsaid first plurality of movable contact springs and a second surfaceengageable with said second plurality of movable contact springs, and abufier spring engaging said core and engageable with said movableoperating card.

4. An electromagnetic relay comprising an E- shaped core having threecoplanar legs and a bridging member, an energizing coil mounted on thecenter one of said legs, a spoolhead for said coil, a plurality ofinsulating members, means for clamping said insulating members and thebridging member of said core in stacked relationship, an armature, meansfor hinging said armature to said core, a molded block, a core plateengaging said core and fixing the location of the ends of the legs ofsaid core, a pair of extensions on said core plate engaging said moldedblock for fixing said block with respect to said core, a plurality offixed contact springs molded in one of said insulating members and insaid block, a first plurality of movable contact springs molded inanother one of said insulating members and extending in spaced proximityto and on one side of said fixed contact springs, a second plurality ofmovable contact springs molded in another one of said insulating membersand extending in space proximity to and on the other side of said fixedcontact springs, a movable operating card engaging said armature andhaving a first surface engageable with said first plurality of movablecon tact springs and a second surface engageable with said secondplurality of movable contact springs, and a U-shaped buffer springcomprising two leg portions engaging said core and said spoolhead, across member engaging said core members, a front and an intermediatemolded,

block, a core plate engaging the three legs of said core, a back-stopprojection on said core plate engageable with said armature, a pair ofL-shaped extensions on said core plate engaging said front molded block,a first plurality of wire springs molded in one of said insulatingmembers and in said front and intermediate molded blocks, a fixedcontact element mounted on each of said first plurality of wire springsadjacent said front ,molded block, a second and a third plurality oftwin-wire springs molded in individual ones of said insulating membersand extending in spaced proximity to said first plurality of wiresprings and on opposite sides thereof, a plurality of projections onsaid front molded block forming slots engaging the individual ones ofsaid second and said third pluralities of springs, a movable operatingcard engaging said armature and having a first surface engageable withsaid second plurality of wire springs and a second surface engageablewith said third plurality of Wire springs, and a balance spring held bysaid clamp and engaging said movable operating card.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,647,792 Gent Nov. 1, 1927 2,472,709 Knapp June '7, 19492,490,963 Hobgaard Dec. 13, 1949 2,562,091 Harrison July 24, 1951

